The invention of the laser was one of the most important scientific and technological developments in the past century. No material is immune to damage from high energy, focused laser beam where the induced electric field is high enough to produce non-linear optical breakdown. Material modification using laser has been possible since the electric fields produced by the laser beam are comparable to the Coulomb field an electron sees in the proximity of the atomic nucleus leading to avalanche ionization. In this process, free electrons in the target material accelerate due to the high electric fields produced by the laser and create an avalanche of free electrons through collisions with other atoms. This process also occurs in transparent materials which become opaque when the free electron density approaches the critical density for that particular light. It is important to note that this optical breakdown has a non-linear dependence on intensity and this allows for the damage to be restricted to the subdiffraction limit by “thresholding” allowing the fabrication of nanoscale features.
Lasers are commonly used for micro-component fabrication. However, use of lasers to form microstructures commonly results in material fractures beyond the zone of ablation, unsuitably regulated ablation positioning, varied aperture and structure dimensions, and use of materials indifferent to the characteristics of photon radiation. Therefore, there is a need for ion passage membranes with channels having substantially uniform and reproducible spacing, dimensions, and arrangement; capable of effective mass production; and extreme nanoscale characteristics.